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* dcrt0.cc (dll_crt0_0): Check for wincap.wow64_has_secondary_stack

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rather than for wincap.is_wow64.  Accommodate name change from
	wow64_has_64bit_parent to wow64_needs_stack_adjustment.  Align comment.
	(_dll_crt0): Ditto.
	* wincap.h (wincaps::wow64_has_secondary_stack): New element.
	* wincap.cc: Implement above element throughout.
	(wincapc::init): Set wow64_has_secondary_stack to false on non-64 bit
	systems.
	* wow64.cc (wow64_needs_stack_adjustment): Rename (hopefully the last
	time) from wow64_has_64bit_parent.
	(wow64_eval_expected_main_stack): Fix comment to reflect real life.
	(wow64_test_for_64bit_parent): Fix comment.
	* wow64.h (wow64_needs_stack_adjustment): Accommodate new name.
This commit is contained in:
Corinna Vinschen
2011-12-19 12:50:35 +00:00
parent 93a61a6fe3
commit f08bc85858
6 changed files with 53 additions and 17 deletions
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23
winsup/cygwin/wow64.cc
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@@ -15,7 +15,7 @@ details. */
#define PTR_ADD(p,o) ((PVOID)((PBYTE)(p)+(o)))
bool NO_COPY wow64_has_64bit_parent = false;
bool NO_COPY wow64_needs_stack_adjustment = false;
static void
wow64_eval_expected_main_stack (PVOID &allocbase, PVOID &stackbase)
@@ -27,10 +27,17 @@ wow64_eval_expected_main_stack (PVOID &allocbase, PVOID &stackbase)
dosheader = (PIMAGE_DOS_HEADER) GetModuleHandle (NULL);
ntheader = (PIMAGE_NT_HEADERS32) ((PBYTE) dosheader + dosheader->e_lfanew);
/* The main thread stack is expected to be located at 0x30000, which is the
case for all observed NT systems to date, unless the stacksize requested
by the StackReserve field in the PE/COFF header is so big that the stack
doesn't fit in the area between 0x30000 and the start of the image. In
case of a conflict, the OS allocates the stack right after the image. */
case for all observed NT systems up to Server 2003 R2, unless the
stacksize requested by the StackReserve field in the PE/COFF header is
so big that the stack doesn't fit in the area between 0x30000 and the
start of the image. In case of a conflict, the OS allocates the stack
right after the image.
Sidenote: While post-2K3 32 bit systems continue to have the default
main thread stack address located at 0x30000, the default main thread
stack address on Vista/2008 64 bit is 0x80000 and on W7/2K8R2 64 bit
it is 0x90000. However, this is no problem because the system sticks
to that address for all WOW64 processes, not only for the first one
started from a 64 bit parent. */
allocbase = (PVOID) 0x30000;
/* Stack size. The OS always rounds the size up to allocation granularity
and it never allocates less than 256K. */
@@ -62,9 +69,9 @@ wow64_test_for_64bit_parent ()
else in the child process.
What we do here is to check if the current stack is the excpected main
thread stack and if not, if we really have been started from a 64 bit
process here. If so, we note this fact in wow64_has_64bit_parent so we
can workaround the stack problem in _dll_crt0. See there for how we go
along. */
process here. If so, we note this fact in wow64_needs_stack_adjustment
so we can workaround the stack problem in _dll_crt0. See there for how
we go along. */
NTSTATUS ret;
PROCESS_BASIC_INFORMATION pbi;
HANDLE parent;